scholarly journals Effects of Surface Roughness and Supply Inertia on Steady Performance of Hydrostatic Thrust Bearings Lubricated with Non-Newtonian Fluids

2021 ◽  
Vol 71 (2) ◽  
pp. 317-328
Author(s):  
Udaya P. Singh
Keyword(s):  
Surface Roughness ◽  
Fluid Inertia ◽  
Film Pressure ◽  
Thrust Bearings ◽  
Lubricant Flow ◽  
Load Carrying ◽  
Analytic Expressions ◽  
Pseudoplastic Fluids ◽  
Strain Model ◽  
Steady Performance

Abstract The objective of present theoretical analysis is to study the combined effects of surface roughness and fluid inertia (including the inertia of the fluid in the supply region) on the steady performance of stepped circular hydrostatic thrust bearings lubricated with non-Newtonian pseudoplastic fluids using Rabinowitsch stress-strain model. To account for the effects of surface roughness, the classical Christensen theory of rough surface has been taken. Analytic expressions for film pressure in bearing regions have been established for radial and circumferential patterns of roughness. Numerical results for film pressure, load carrying capacity and lubricant flow rate has been plotted and analysed. Due to surface roughness and fluid inertia in overall regions, significant improvement in performance properties have been observed.

Analysis of hydrostatic rough thrust bearing lubricated with Rabinowitsch fluid considering fluid inertia in supply region

2020 ◽  
pp. 135065012094588
Author(s):  
Udaya P Singh ◽  
Prawal Sinha ◽  
Mukesh Kumar
Keyword(s):  
Experimental Data ◽  
Surface Roughness ◽  
Thrust Bearing ◽  
Fluid Model ◽  
Momentum Equation ◽  
Fluid Inertia ◽  
Static Properties ◽  
Roughness Effects ◽  
Film Pressure ◽  
Analytic Expressions

With the advancement of lubrication technology, precise prediction of performance characteristics of bearings is the first and inevitable step for stability of mechanical systems. Most of the existing theoretical analyses of hydrostatic thrust bearings lubricated with non-Newtonian fluids have considered the lubricant inertia, only in the recess and land regions but did not account either for the inertia of lubricant in the supply region or the surface roughness of the bearings. This could be a cause for the deviation between the theoretical results and the experimental data under certain conditions. In this work, combined influence of surface roughness as well as lubricant inertia in the supply region, on the static properties of a hydrostatic stepped thrust bearing lubricated with a non-Newtonian fluid, has been discussed using Rabinowitsch fluid model. Surface roughness effects have been accounted for using Christensen theory of rough surfaces. It is expected that the current study could bridge the gap between the experimental and theoretical studies. Solution for momentum equation has been obtained by means of average inertia approach. Analytic expressions for film pressure have been derived for radial and circumferential roughness patterns. Mathematica 11.0 has been used for numerical computations, wherever necessary. Results for film pressure and load carrying capacity have been plotted and discussed. It is observed that the present results are in a better agreement with the experimental data.

scholarly journals EFFECT OF SURFACE ROUGHNESS ON STEADY PERFORMANCE OF HYDROSTATIC THRUST BEARINGS: RABINOWITSCH FLUID MODEL

2019 ◽  
Author(s):  
Udaya Pratap Singh
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Load Capacity ◽  
Numerical Results ◽  
Integral Approach ◽  
Load Carrying Capacity ◽  
Film Pressure ◽  
Thrust Bearings ◽  
Longitudinal Roughness ◽  
Load Carrying

Purpose of the present theoretical investigation is to analyze the effects of surface roughness on the steady-state performance of stepped circular hydrostatic thrust bearings lubricated with non-Newtonian Rabinowitsch type fluids. Results for film pressure and load-carrying capacity have been plotted and analyzed on the basis of numerical results. To take the effects of surface roughness into account, Christensen theory of rough surface has been adopted. The expression for pressure gradient has been derived by means of the energy integral approach. This approach avoids the derivation of Reynolds’ equation. The numerical results for film pressure and load capacity have been obtained using Mathematica. It was observed that in comparison with smooth surfaces, dimensionless film pressure and load capacity is lower for longitudinal roughness and higher for circular roughness patterns with and the variations are significant. Load carrying capacity decreases with the increase of longitudinal roughness and, increases with the increase of circular roughness. Further, the effects of surface roughness and non-Newtonian lubricants are significant for larger values of inertia parameter. Because of the closeness of results to the experimental values, this study will be helpful in the design of circular hydrostatic thrust bearings.

Numerical Investigations of Various Surface Roughness Parameters on the Performance of Profiled Hydrostatic Thrust Bearing

2005 ◽  
Author(s):  
Kirat Shah ◽  
Robert E. Johnson ◽  
Harish P. Cherukuri
Keyword(s):  
Surface Roughness ◽  
Thrust Bearings ◽  
Lubrication Equation ◽  
Load Carrying ◽  
Minimum Film Thickness ◽  
Order Of Magnitude ◽  
Auto Correlation Function ◽  
Non Gaussian ◽  
Gaussian Surface ◽  
Lubrication Conditions

Measurements of surface roughness on hydrostatic bearing slipper indicate that the surfaces are not always Gaussian. Previous studies in this area were primarily concerned with Gaussian surfaces. In this research the effects of non-Gaussian surface roughness on the performance of profiled hydrostatic thrust bearings are analyzed. This study is applicable to the lubrication conditions where the surface roughness is of the same order of magnitude as the minimum film thickness. Surfaces with different skewness, kurtosis, mean, auto-correlation function and standard deviation are generated numerically using a combination of Fast Fourier Transform (FFT) and Johnson translatory system. The finite difference method is used to solve the Reynolds lubrication equation. The effect of roughness on the load carrying capacity is investigated and compared with the results for ideal smooth surfaces.

The Effects of Fluid Inertia Forces on the Static Characteristics of Sector-Shaped, High-Speed Thrust Bearings in Turbulent Flow Regime

1989 ◽  
Vol 111 (3) ◽  
pp. 406-412 ◽  
Author(s):  
H. Hashimoto
Keyword(s):  
Carrying Capacity ◽  
High Speed ◽  
Experimental Results ◽  
Polar Coordinates ◽  
Load Carrying Capacity ◽  
Static Characteristics ◽  
Fluid Inertia ◽  
Thrust Bearings ◽  
Load Carrying ◽  
Inertia Forces

This paper describes a study on the performance characteristics of sector-shaped, high-speed thrust bearings subjected to the effects of both turbulence and fluid inertia forces. The basic lubrication equations are derived by integrating the momentum and continuity equations in the polar coordinates including the full inertia terms throughout the film thickness; and a numerical calculation technique combining the control volume integration and the Newton-Raphson linearization method is applied to solve the equations. The static characteristics such as the load carrying capacity and the pressure center are calculated for various values of pad extent angle and inner-to-outer radius ratio of a pad. The theoretical results of the load carrying capacity are compared with the experimental results. It was found that the fluid inertia forces have significant effects on the static characteristics of the bearings. Good agreement was obtained between theoretical and experimental results.

scholarly journals THERMOHYDRODYNAMIC PERFORMANCE OF A JOURNAL BEARING WITH 3D-SURFACE ROUGHNESS AND FLUID INERTIA EFFECTS

2012 ◽  
pp. 243-249
Author(s):  
E. SUJITH PRASAD ◽  
T. NAGARAJU ◽  
J. PREM SAGAR
Keyword(s):  
Surface Roughness ◽  
Journal Bearing ◽  
Roughness Parameter ◽  
Theoretical Work ◽  
Fluid Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
3D Surface Roughness ◽  
Load Carrying ◽  
Hydrodynamic Journal Bearing

This theoretical work describe the combined influence of surface roughness, thermal and fluid-inertia effects on performance characteristics of hydrodynamic journal bearing. The average Reynolds equation that modified to include the surface roughness, viscosity variation due to temperature rise in lubricant fluid-film and fluid-inertia is used to obtain pressure field in the fluid-film. The matched solutions of modified average Reynolds, energy and conduction equations are obtained using finite element method and appropriate iterative schemes. The effects of surface roughness parameter, roughness orientation, and roughness characteristics of opposing surfaces on circumferential fluid-film pressure distribution, load carrying capacity and stability threshold speed of the bearing are studied by considering thermal and fluid-inertia effects.

scholarly journals Effect of Surface Roughness on MHD Couple Stress Squeeze-Film Characteristics between a Sphere and a Porous Plane Surface

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
M. Rajashekar ◽  
Biradar Kashinath
Keyword(s):  
Surface Roughness ◽  
Carrying Capacity ◽  
Couple Stress ◽  
Hydrodynamic Lubrication ◽  
Plane Surface ◽  
Squeeze Film ◽  
Load Carrying Capacity ◽  
Film Pressure ◽  
Load Carrying ◽  
The Mean

The combined effects of couple stress and surface roughness on the MHD squeeze-film lubrication between a sphere and a porous plane surface are analyzed, based upon the thin-film magnetohydrodynamic (MHD) theory. Using Stoke’s theory to account for the couple stresses due to the microstructure additives and the Christensen’s stochastic method developed for hydrodynamic lubrication of rough surfaces derives the stochastic MHD Reynolds-type equation. The expressions for the mean MHD squeeze-film pressure, mean load-carrying capacity, and mean squeeze-film time are obtained. The results indicate that the couple stress fluid in the film region enhances the mean MHD squeeze-film pressure, load-carrying capacity, and squeeze-film time. The effect of roughness parameter is to increase (decrease) the load-carrying capacity and lengthen the response time for azimuthal (radial) roughness patterns as compared to the smooth case. Also, the effect of porous parameter is to decrease the load-carrying capacity and increase the squeeze-film time as compared to the solid case.

scholarly journals Shear cutting induced residual stresses in involute gears and resulting tooth root bending strength of a fineblanked gear

2021 ◽  
Author(s):  
Daniel Müller ◽  
Jens Stahl ◽  
Anian Nürnberger ◽  
Roland Golle ◽  
Thomas Tobie ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Residual Stresses ◽  
Carrying Capacity ◽  
Bending Strength ◽  
Tooth Root ◽  
Load Carrying Capacity ◽  
Near Surface ◽  
Load Carrying ◽  
Involute Gears ◽  
Cut Surface

AbstractThe manufacturing of case-hardened gears usually consists of several complex and expensive steps to ensure high load carrying capacity. The load carrying capacity for the main fatigue failure modes pitting and tooth root breakage can be increased significantly by increasing the near surface compressive residual stresses. In earlier publications, different shear cutting techniques, the near-net-shape-blanking processes (NNSBP’s), were investigated regarding a favorable residual stress state. The influence of the process parameters on the amount of clean cut, surface roughness, hardness and residual stresses was investigated. Furthermore, fatigue bending tests were carried out using C-shaped specimens. This paper reports about involute gears that are manufactured by fineblanking. This NNSBP was identified as suitable based on the previous research, because it led to a high amount of clean cut and favorable residual stresses. For the fineblanked gears of S355MC (1.0976), the die edge radii were varied and the effects on the cut surface geometry, hardness distribution, surface roughness and residual stresses are investigated. The accuracy of blanking the gear geometry is measured, and the tooth root bending strength is determined in a pulsating test rig according to standardized testing methods. It is shown that it is possible to manufacture gears by fineblanking with a high precision comparable to gear hobbing. Additionally, the cut surface properties lead to an increased tooth root bending strength.

Rough Air-Soft Elastohydrodynamic Lubrication

2013 ◽  
Vol 420 ◽  
pp. 30-35
Author(s):  
Khanittha Wongseedakaew ◽  
Jesda Panichakorn
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Modulus Of Elasticity ◽  
Contact Region ◽  
Elastohydrodynamic Lubrication ◽  
Multilevel Methods ◽  
Inlet Temperature ◽  
Film Pressure ◽  
Air Inlet ◽  
Air Film

This paper presents the effects of rough surface air-soft elastohydrodynamic lubrication (EHL) of rollers for soft material under the effect of air molecular slip. The time independent modified Reynolds equation and elasticity equation were solved numerically using finite different method, Newton-Raphson method and multigrid multilevel methods were used to obtain the film pressure profiles and film thickness in the contact region. The effects of amplitude of surface roughness, modulus of elasticity and air inlet temperature are examined. The simulation results showed surface roughness has effect on film thickness but it little effect to air film pressure. When the amplitude of surface roughness and modulus of elasticity increased, the air film thickness decreased but air film pressure increased. However, the air inlet temperature increased when the air film thickness increased.

Effect of Rolling Velocity and Maximum Hertzian Pressure on Fluid Film in Steady State EHL Line Contact with Rough Surface and Linear Piezoviscosity

2014 ◽  
Vol 592-594 ◽  
pp. 1371-1375
Author(s):  
Nitesh Talekar ◽  
Punit Kumar
Keyword(s):  
Surface Roughness ◽  
Steady State ◽  
Film Thickness ◽  
Rough Surface ◽  
Computer Code ◽  
Fluid Film ◽  
Line Contact ◽  
Rolling Velocity ◽  
Load Carrying ◽  
Lubricated Contact

Consideration of surface roughness in steady state EHL line contact is the first step towards understanding the lubrication of rough surface problem. Current paper investigates the use of sinusoidal waviness in the contact; more precisely it gives performance of real fluid in EHL line contact. The effect of various parameters like rolling velocity (U) and maximum Hertzian pressure (ph) on surface roughness by using properties of linear and exponential piezo-viscosity is taken into consideration to evaluate behavior of pressure distribution of load carrying fluid film and film thickness. Full isothermal, Newtonian simulation of EHL problem gives described effects. Spiking or fluctuation of pressure and film thickness curves is expected to show presence of irregularities on the surface chosen and amount of fluctuation depends on certain parameters and intensity of irregularities present. Rolling side domain of-4.5 ≤ X ≤ 1.5 with grid size ∆X=0.01375 is selected. A computer code is developed to solve Reynolds equation, which governs the generation of pressure in the lubricated contact zone is discritized and solved along with load balance equation using Newton-Raphson technique.

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